Certain elemental metals may have desirable properties such as, e.g., high conductivity or corrosion resistance and yet be deficient in other respects such as, e.g., tensile strength, hardness, or abrasion resistance.
Pure copper, for example, its excellent conductivity notwithstanding, may be unsuitable for certain electrical applications due to its relatively low tensile strength and hardness. In particular, pure copper may not be suited as an electrical wire material in situations where substantial lengths of wire are pulled through ducts in the course of installation. Similarly, pure gold has excellent corrosion resistance but may be too soft to serve as a contact material in heavy duty mechanical contact applications. In view of such and similar applications, means are desired for fabricating high-strength metallic articles.
According to one line of development, alloys such as, e.g., Cu alloys having high conductivity, strength, and hardness are produced by internal oxidation of an easily oxidized solute additive. In particular, U.S. Pat. No. 3,184,835, "Process for Internally Oxidation-Hardening Alloys, and Alloys and Structures Made Therefrom.revreaction., issued May 25, 1965 to Charles D. Coxe et al. discloses single phase Cu alloys containing beryllium oxide or aluminum oxide. Two-phase oxidation hardened alloys are disclosed in U.S. Pat. No. 3,922,180, "Method for Oxidation-Hardening Metal Alloy Compositions, and Compositions and Structures Therefrom", issued Nov. 25, 1975 to E. O. Fuchs et al. which discloses copper alloys containing zirconium or hafnium oxide.
Relevant in connection with the invention is a field of metallurgical technology known as powder metallurgy which broadly encompasses the molding of shaped metallic articles by methods involving compacting a powder. For example, powder metallurgical processing may involve compacting a metallic powder into a desired shape, followed by sintering, i.e., consolidating the shaped article by heat treatment. Alternatively, processing may call for compacting a metal precursor such as, e.g., a mixture of oxides, followed by reduction and sintering. Methods of this type are disclosed, e.g., in Swedish Pat. No. 127,524, "Process for the Production of Metal Parts and Semimanufactured Metal Parts from Reducible Powdered Metal Compounds by Compacting and Sintering", published Feb. 28, 1950 in the name of H. G. G. Zapf and French Pat. No. 1,100,993, "Improvements in the Preparation of Metal Alloys in Powder Form or in Compact Sintered Pieces", published Sept. 27, 1955 in the name of S. Medvedieff. The preparation of intimate mixtures in powdered form is facilitated by methods such as, e.g., freeze drying as disclosed in U.S. Pat. No. 3,516,935, "Compacted Body and Method of Formation", issued June 23, 1970 to Frank R. Monforte et al.